The polymerization of olefins such as ethylene and propylene is a very important commercial activity, and such polymers in various forms are made in enormous quantities for very many uses. Various methods are known for polymerizing olefins, such as free radical polymerization of ethylene, and coordination polymerization using catalysts such as Ziegler-Natta-type and metallocene-type catalysts. Nevertheless, given the importance of polyolefins new catalysts are constantly being sought for such polymerizations, to lower the cost of production and/or make new, and hopefully improved, polymer structures. More recently so-called single site catalysts using late transition metal complexes have been developed, and they have proved in many instances to give different polymers than the earlier known early transition metal catalysts. See, for example, U.S. Pat. No. 5,714,556, U.S. Pat. No. 5,880,241 and U.S. Pat. No. 6,103,658 (all of which are incorporated by reference herein for all purposes as if fully set forth).
Another type of useful polyolefin is one that contains polar comonomers, such as acrylates. These copolymers are made especially well by a new type of complex in which a certain type of ligand is used.